This invention is concerned with apparatus for analyzing particulate material, such as powders of various types.
My prior U.S. Pat. No. 4,519,244, issued May 28, 1985, and incorporated herein by reference, discloses apparatus and methods for analysis of particulate material by, for example, passing a sample of the material through a series of sieves in a column. Particle characterization is based upon residence time of particles within the column. Particles of different shape, even though their "size" is the same, will pass through a sieve at different rates and will appear at the output of the column at different times, for detection. By virtue of the patented invention, grain, abrasives, and other particulate material can be evaluated with respect to desired qualities. The analysis technique resembles fluid chromatography in certain respects and is referred to as sieve cascadography.
Although ideally the entire sample passes through the sieve column, in practice it has been found that a substantial amount of particulate material may accumulate in the spaces between successive sieves (inter-sieve spaces). In prior sieve cascadographs comprising a series of sieve units stacked and assembled to form the sieve column, the column may be disassembled and the sieves separated to gain access to the inter-sieve spaces for clean-out of accumulated particles. However, the sieves may be formed of fragile material that is easily damaged during cleaning. In any event the assembly and disassembly of the sieves is a laborious procedure.